Sampling and questionnaires.
Perez-Fernandez
V
V
Area de Pediatría. Universidad de Murcia. El Palmar. Murcia. Spain. virperez@um.es
D003627:Data Interpretation, Statistical; D006801:Humans; D012107:Research Design; D012494:Sampling Studies; D012984:Software; D011795:Surveys and Questionnaires